Illinois 9 just might be the longest east-west running state route in Illinois. (Illinois 16 also makes a likely candidate.) IL9 spans the whole state from the Indiana border near Hoopeston to the Mississippi River at Niota near Ft. Madison, Iowa.
Intersections (from west to east):
IL9 joins IL96 at Niota, then parts with it at Dallas City
Then IL94 joins from the south
IL94 departs toward the north
IL41 joins from the south at Bushnell
IL41 goes off north
IL97 joins for a couple miles from the south
IL97 leaves north
IL78 joins from the north at Canton
IL78 leaves to the south
US24 joins IL9 going westbound
IL9 leaves US24 to cross the Illinois River and bypass Peoria
IL29 at Pekin
I-155 by Tremont
US150 joins IL9 from the west near Bloomington
Business US51 at Bloomington
US150 leaves to the SE
Business I-55 still at Bloomington
IL9 joins IL47 in Gibson City
Then IL54 joins the 2 routes
Then IL47 leaves to the south
Next, IL54 leaves to the NE
US45 at Paxton
IL49 near Rankin
IL1 near Hoopeston
Towns: Niota, Dallas City, La Harpe, Blandinsville, Bushnell, Canton, Kingston Mines, Pekin, Tremont, Mackinaw, Bloomington, Gibson City, Paxton, Hoopeston.
Notable places: Mackinaw River State Wildlife Refuge is only a mile off of IL9.
Moraine View SP is one of the state's premiere state parks. It's 4 miles south of IL9 near Ellsworth.
When crossing into Indiana IL9 becomes IN26.
